Compressor



Dec. 2, 1969 COMPRESSOR Filed Deo. 20, 1967 AGENT United States Patent O 3,481,532 COMPRESSOR Grover D. Fraser, Painted Post, N.Y., assignor to Ingersoll-Rand Company, New York, N.Y., a corporation of New Jersey Filed Dec. 20, 1967, Ser. No. 692,252 Int. Cl. F04c 17/12, 25/00 U.S. Cl. 230-143 7 Claims ABSTRACT OF THE DISCLOSURE A two-stage,j helical lobe, gas compressor having the two stages in an offset, bi-level relationship conservative of structural length and elevation, and balancing gas load force on the male rotors. Terminal inlets and centrally disposed outlets, and high pressure oil injection, are provided to counter thrust loading.

This invention relates to compressors and in particular to an improved two-stage, oil-flooded, helical lobe, gas compressor.

In prior art two-stage, helical lobe compressors it is customary to arrange the two stages in line, forming an extended structure requiring considerable installation space. Other prior art two-stage gas compressors, alternatively, are arranged with the stages in surmounting relationship, creating an extremely tall structure. The inline type of prior art gas compressors have structural lengths that are dictated by the sum of the extended length of each stage and, in addition, the dimension necessary between the stages for the journaling of the shafts. The surmounting type or elevated type of two-stage compressors have structural heights dictated by the radii of the rotors in stacked relationship and, in addititon, the space required for the volutes for inlet and outlet chambers.

The prior art in-line, two-stage compressors customarily dispose the inlets and outlets at same, corresponding positions for each stage. That is, the inlet for the first stage would be on a terminal end of the stage, and its outlet at the opposite end thereof feeding to the immediately adjacent inlet of the second stage, with the second stage terminating at the opposite end of said second stage. This arrangement creates an in-line, unrelieved thrust loading of thefcompressor.

It is an object of this invention to overcome the limitations seen in prior art two-stage compressors, by providing a two-stage, gas compressor having an enhanced geometrical packaging requiring less extended and elevational space. Another object of this invention is to provide means for effecting a dynamic balancing to counteract the thrust normally developed in the rotor shafts.

A feature of this invention comprises the first stage male rotor in line with, and coupled to, the second stage male rotor shaft, and having the female rotors of the two stages disposed one above and the second below their respective male rotors so as to define a combination of surmounting and in-line stages; that is, offset .or bi-level stages. This is the teaching of a preferred embodiment of the invention as set forth herein. However, clearly an alternate embodiment, within the spirit of myinvention, could contemplate a compressor rotated 90, or more or less. In this the offset stages would be laterally disposed, and the inlet, outlet, and inter-stage ducting would be disposed above and below, rather than having the latter side-mounted as taught by the bi-level configuration presented herein. The practice of forming either one or the other will be dictated by the accommodations and convenient disposition of loading in the Work area or place of use.

Another feature of this invention comprises having the Patented Dec. 2, 1969 inelts for the first and second stages at the opposite, terminal ends of the machine, and the outlets centrally located therebetween. Further objects and features of this invention will become more apparent by reference to the following description taken in conjunction with the figures in which:

FIGURE 1 is a plan view of the gas compressor according to the invention; and

FIGURE 2 is an elevational view, in cross-section, of the gas compressor of FIG. l.

As shown in FIG. 1, the novel compressor has a first stage 1, and a second stage 2, with side-mounted inlet and outlet ports. FIG. 2 more clearly illustrates the two stages in off-set, bi-level relationship- The female rotor 3 of the first stage is shown mounted above the first stage male rotor 4. The male rotor 5 of the off-set second stage is shown coupled, in line, with the male rotor 4 of the first stage, and its mating female rotor 6 is shown mounted there below. The two male rotors 4, 5 are mounted together, in line, on male rotor shaft 7. Male rotor shaft 7 is integral with second stage male rotor 5, in this embodiment. First stage male rotor 4 is mounted on a portion of shaft 7 extending from rotor 5, and is secured thereto by a fastener 8.

This mounting arrangement of the male rotors 4 and 5 is wholly arbitrary. Other arrangements, equally within the spirit of my invention, will occur to others. For instance, the shaft 7 can be totally separate of the rotors, there being provided means for fastening each rotor thereto; alternatively, the shaft 7 could be integral with first stage male rotor `4.

The first stage inlet 9 is shown as a port with an associated volute 10 about the outer end of the first stage 1. The first stage outlet 11 is seen venting out of the central area of the machine. The second stage inlet 12 is shown with its associated volute 13 at the opposite terminal end of the machine. The discharge or outlet 14 of second stage 2, is disposed adjacent the inner end of rotor 6.

Apertures 15 are provided in bearing caps 16 for the feeding of high-pressure oil to the second stage rotors 5 and 6, to counter the axial thrust of the second stage and to lubricate the shaft bearings 17. Apertures 15 have check valves, or the like (not shown), to prohibit a reverse flow of oil outward therefrom. Port 18, formed in housing 19 adjacent the inner journaled end of second stage female rotor 6, is an oil inlet for shaft bearing 20; port 18 also, like apertures 15, has a check valve, or the like (not shown). Means not shown, but widely known and practiced in the art, provide for oil injection, directly into the first stage compression chamber l 21, for sealing and cooling, and for lubrication of bearings 22 through 25. Oil put into the compressor is carried out with the discharging compressed gas and can be removed therefrom by means of a separator.

The first stage outlet 11 is conducted to the second stage inlet 12, in the direction of the arcuate arrow (FIG. l) by means of piping (not shown) throughconnecting therebetween and secured to flanges 26 and 27.

Shims 28 are disposed within the bearing and end caps 1-6, 29 of each stage to provide for proper adjustment of rotor-to-housing axial clearance. The end caps 29 and 30 of the first stage and the bearing caps 1-6 of the second stage close and seal the rotor chambers 21 Iand 31. Also,

thrust bearings 32 are disposed between bearing caps 16 and the shaft ends of rotors 5 and l6. Finally, a source of high-pressured oil 33 is coupled to apertures 15, and drive means (not shown) power the compressor by rotating an extending section 7 of shaft 7.

As can be seen from the drawings, each stage develops a thrust toward the opposite terminal ends of the machine but, as the discharge for each is centrally located, the thrust loading of the male rotor shafts is partly compensated; the axial urgings of each of the male rotors are in opposition. This provides a novel dynamic balance of much of the normally developed thrust loading. Further, the high pressure oil supplied to the secand stage via bearing caps 16 additionally overcomes some of the thrust developed in the second stage. This, in combination, provides a largely dynamically balanced, two-stage, axial compressor. Also, the geometric packaging taught by the instant disclosure provides -a compressor offering a less gross conguration.

My disclosure teaches the coupling of outwardly thrusted male rotors 4 and S on a common shaft 7, to derive therefrom ya mutual counter-action of the individually developed thrust loading of each individual male rotors. Self-evidently, an alternate embodiment of my novel compressor can contemplate inwardly thrusted male rotors, on a common shaft, providing mutually canceling thrust loading. In such a latter arrangement, the gas inputs would be disposed centrally of the compressor, and the outputs would be near the terminal ends thereof. And such an alternate embodiment would be, clearly, within the spirit of my invention as described herein.

While I have described my invention in connection with a specific embodiment it is to be clearly understood that this is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. A gas compressor, comprising: an elongate housing; iirst and second compressor stages disposed therein; said stages together having `a pair of means for the inlet of gas to, and a pair of means for the outlet of gas from, said stages; wherein one of said pair of means is disposed adjacent the ends of said housing; land said other pair of means is disposed centrally of said housing; and further including rst means coupled to one of said stages for countering axial thrust developed by said one stage and for lubricating said one stage;

said rst means comprising means for impelling pressurized oil against said one stage; and wherein said rst and second stages each have male and female rotors, said male rotors are coupled together in line, said female rotors are parallel to each other, each of 4 said male rotors is in meshing engagement with only one of said female rotors, and said male rotors are disposed on a common shaft which is intermediate of said female rotors.

2. A gas compressor, according to claim 1, wherein: said one pair is said pair of inlet means.

3. A gas compressor, according to claim 1, wherein: one of said stages is disposed to develop axial thrust in a given direction, and the other of said stages is disposed to develop axial thrust in a direction other than said given direction.

4. A gas compressor, according to claim 1, wherein: one of said stages is disposed to develop axial thrust in a given direction, and the other of said stages is disposed to develop Iaxial thrust in a direction counter to said given direction.

5. A gas compressor, according to claim 1, further including second means coupled to said one stage for countering said axial thrust.

6. A gas compressor, according to claim 5, wherein: said second means comprise the other of said stages.

7. A gas compressor, according to claim 1, wherein: said first and second stages have a given axis common to both and are coupled together therealong; said first stage has a further axis other than said given axis; and said second stage has a further yaxis distinct from said given and said other axis.

References Cited UNITED STATES PATENTS 1,698,802 l/ 1929 Montelius 10S-128 2,100,560 11/1937 Kennedy 10S-128 2,581,451 l/l952 Sennet 103-128 2,659,239 11/1953 Nilsson et al 10S-128 2,804,260 8/1957 Nilsson et al 230-143 3,279,682 10/1966 Vagenius 230-143 DONLEY J. STOCKING, Primary Examiner WILBUR I. GOODLIN, Assistant Examiner U.S. Cl. X.R. 

